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Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
9/28/15 3:53 p.m.
SSATB wrote: I read somewhere that a well designed MacPherson setup is easier to drive at the limit and it isn't as inferior to double wishbone as is always claimed. One of best handling cars ever made is the Cayman. It's possible one of the reasons Porsche went with MacPherson all around is because, especially in the back, there probably isn't much space with the MR transaxle for a triangulated A-arm. 1) Do MacPherson struts offer any handling/ride quality advantages over DWB, for *road cars?* 2) Which, front engine, rear-wheel drive (FR) cars have MacPherson struts at all four corners (like the Cayman)?

I passed a Cayman S on the track this weekend. I was driving a 155 hp Miata with double wishbones in the front and a multilink in the back. He couldn't corner with me, despite his Nitto NT-01s. So I reject your struts!

He had to basically put it in reverse to let me past on the straight, though.

Appleseed
Appleseed MegaDork
9/28/15 4:26 p.m.

The other nice thing about Mac struts is that a 7kg spring acts like a 7kg spring instead of figuring out percentages when the spring is farther inboard.

Knurled
Knurled GRM+ Memberand UltimaDork
9/28/15 4:37 p.m.
sethmeister4 wrote:
Trackmouse wrote: 240z is dwb all four corners.
Pretty sure it's not at all. Struts front and rear, I think the rear is a semi trailing arm style, not totally sure if I have that right. Front is definitely strut, no DWBs anywhere.

Easy way to remember - Z is struts, ZX is swingarms.

Knurled
Knurled GRM+ Memberand UltimaDork
9/28/15 4:41 p.m.
Appleseed wrote: The other nice thing about Mac struts is that a 7kg spring acts like a 7kg spring instead of figuring out percentages when the spring is farther inboard.

It's close enough for back of envelope calculations, and it's the factor I use with good success, but there's still a motion ratio, depending on the angle of the strut and the way it attaches to the upright. It's rarely much more than 1.05:1 or so but it isn't a straight rate.

Now the noodle baker. Solid axles. Are they a 1:1 motion ratio when in one wheel bump? Bear in mind that you will be moving BOTH springs if the chassis remains stationary...

iceracer
iceracer PowerDork
9/28/15 6:28 p.m.

Escorts

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
9/28/15 6:39 p.m.
Knurled wrote:
GameboyRMH wrote: When the arm passes the level position in compression travel, the camber curve reverses itself
This is incorrect. The camber curve does not change signs until the angle defined by strut top - ball joint (or other pivot) - inner control arm/TCA pivot goes obtuse. Until that point, camber does still go more negative with bump travel.

That's a better way to put it, but that's the same thing as what I added about the strut angle - level assuming the strut is vertical.

mad_machine
mad_machine GRM+ Memberand MegaDork
9/28/15 7:09 p.m.

One of the best handling cars ever has struts all the way around.. in fact the rear suspension is the exact same as the front suspension on a FWD sedan.. I am talking about the Fiat X 1/9. The Front was struts up front and the rear was the front suspension from the 128 moved back. It even had the linkages from the 128's steering rack that was used to control toe

Knurled
Knurled GRM+ Memberand UltimaDork
9/28/15 7:40 p.m.
GameboyRMH wrote: That's a better way to put it, but that's the same thing as what I added about the strut angle - level assuming the strut is vertical.

The struts are never vertical, though. Steering axis inclination is generally 7-12 degrees or so.

It gets more tricky if the strut is not inline with the ball joint/outer pivot. The goofy stuff Ford did with the Fox-body's strut mounting was so they could get antidive and a decent camber curve while keeping the ball joint taper close to the spindle for strength (less iron too, probably/mostly ) Only downside is they did some righteously bad things with the scrub radius in the process.

Chas_H
Chas_H New Reader
9/28/15 8:38 p.m.

In reply to Knurled:

Struts can be verticle, or close to it. The spring axis does not necessarily need to be concentric with the steering axis. See Porsche 935 or even VW Rabbit.

SSATB
SSATB New Reader
9/29/15 5:58 p.m.

Love threads like these where all kinds of geeky info is unearthed. Thank you everyone for your contribution.

So far, no FR car has been identified with MacPhersons front and back. Does that mean none exist?

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